feat(chat): 聊天排版升级微信标准(左右分侧+头像+绿气泡)+is_send数据修复

- is_send 根因:云客消息方向在 mine 字段(isSend 全 null),归一化加 fallback
  +存量回填 60.7 万行(51万收/16万发)——分侧数据首次完整
- MessageBubble:头像(对方=raw headUrl 在左/自己=默认在右)、自己侧隐藏昵称、
  接收白底描边/发送微信绿 #95ec69、气泡列 max-width 78%
- 实测混合对话:13发(绿+头像右)/7收(白+头像左)全部正确

Co-Authored-By: Claude <noreply@anthropic.com>

yunkes/src/style.css

@@ -142,7 +142,7 @@ a {
 .yk-msg {
   display: flex;
   width: 100%;
-  padding: 6px 0;
+  padding: 4px 0;
 }
 
 .yk-msg--send {
@@ -151,14 +151,46 @@ a {
 
 .yk-msg__row {
   display: flex;
-  flex-direction: column;
-  max-width: 70%;
+  max-width: 78%;
+  gap: 10px;
+  align-items: flex-start;
 }
 
 .yk-msg--send .yk-msg__row {
+  flex-direction: row-reverse;
+}
+
+.yk-msg__body {
+  display: flex;
+  flex-direction: column;
+  min-width: 0;
+}
+
+.yk-msg--send .yk-msg__body {
   align-items: flex-end;
 }
 
+/* 头像(微信式):对方在左/自己在右(row-reverse),小圆角方形 */
+.yk-msg__avatar-wrap {
+  flex: none;
+}
+
+.yk-msg__avatar {
+  width: 38px;
+  height: 38px;
+  border-radius: 4px;
+  object-fit: cover;
+  display: block;
+  background: #f2f3f5;
+}
+
+.yk-msg__avatar--ph {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: #a8abb2;
+}
+
 /* Clickable bubble row — opens the all-fields drawer. Subtle hover so users
  * discover the interaction without changing the bubble's own look. */
 .yk-msg__row--clickable {
@@ -186,8 +218,9 @@ a {
 
 .yk-msg__bubble {
   padding: 8px 12px;
-  border-radius: 10px;
-  background: #f4f4f5;
+  border-radius: 8px;
+  background: #ffffff;
+  border: 1px solid #e5e6eb;
   color: #303133;
   line-height: 1.5;
   word-break: break-word;
@@ -195,8 +228,9 @@ a {
 }
 
 .yk-msg--send .yk-msg__bubble {
-  background: var(--el-color-primary-light-8, #d9ecff);
-  color: #1d2129;
+  background: #95ec69;
+  border-color: #95ec69;
+  color: #0f170a;
 }
 
 .yk-msg__image {